Problem: Write a program that will read the full list of customers and output the names and user ids of matching customers (within 100km), sorted by user id (ascending).

Customer.java

package br.com.rmxs.intercom.entity;

/**
 * Created by rmxsantiago on 7/29/15.
 */
public class Customer {
    private long user_id;
    private String name;
    private double latitude;
    private double longitude;


    public Double getLongitude() {
        return longitude;
    }

    public void setLongitude(String longitude) {
        this.longitude = Double.parseDouble(longitude);
    }

    public Double getLatitude() {
        return latitude;
    }

    public void setLatitude(String latitude) {
        this.latitude = Double.parseDouble(latitude);
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public long getUser_id() {
        return user_id;
    }

    public void setUser_id(long user_id) {
        this.user_id = user_id;
    }

    @Override
    public String toString() {
        String separator = " - ";
        StringBuilder builder = new StringBuilder();
        builder.append("Id: " + getUser_id());
        builder.append(separator);
        builder.append("Name: " + getName());
        /*builder.append(separator);
        builder.append("latitude " + getLatitude());
        builder.append(separator);
        builder.append("longitude " + getLongitude());*/

        return builder.toString();
    }
}

CustomerComparator.java

package br.com.rmxs.intercom.comparator;


import br.com.rmxs.intercom.entity.Customer;

import java.util.Comparator;

/**
 * Created by rmxsantiago on 7/29/15.
 */
public class CustomerComparator implements Comparator<Customer> {
    @Override
    public int compare(Customer o1, Customer o2) {
        return (o1.getUser_id() < o2.getUser_id()) ? -1 : 1;
    }
}

customers.json

[{"latitude": "52.986375", "user_id": 12, "name": "Christina McArdle", "longitude": "-6.043701"},
{"latitude": "51.92893", "user_id": 1, "name": "Alice Cahill", "longitude": "-10.27699"},
{"latitude": "51.8856167", "user_id": 2, "name": "Ian McArdle", "longitude": "-10.4240951"},
{"latitude": "52.3191841", "user_id": 3, "name": "Jack Enright", "longitude": "-8.5072391"},
{"latitude": "53.807778", "user_id": 28, "name": "Charlie Halligan", "longitude": "-7.714444"},
{"latitude": "53.4692815", "user_id": 7, "name": "Frank Kehoe", "longitude": "-9.436036"},
{"latitude": "54.0894797", "user_id": 8, "name": "Eoin Ahearn", "longitude": "-6.18671"},
{"latitude": "53.038056", "user_id": 26, "name": "Stephen McArdle", "longitude": "-7.653889"},
{"latitude": "54.1225", "user_id": 27, "name": "Enid Gallagher", "longitude": "-8.143333"},
{"latitude": "53.1229599", "user_id": 6, "name": "Theresa Enright", "longitude": "-6.2705202"},
{"latitude": "52.2559432", "user_id": 9, "name": "Jack Dempsey", "longitude": "-7.1048927"},
{"latitude": "52.240382", "user_id": 10, "name": "Georgina Gallagher", "longitude": "-6.972413"},
{"latitude": "53.2451022", "user_id": 4, "name": "Ian Kehoe", "longitude": "-6.238335"},
{"latitude": "53.1302756", "user_id": 5, "name": "Nora Dempsey", "longitude": "-6.2397222"},
{"latitude": "53.008769", "user_id": 11, "name": "Richard Finnegan", "longitude": "-6.1056711"},
{"latitude": "53.1489345", "user_id": 31, "name": "Alan Behan", "longitude": "-6.8422408"},
{"latitude": "53", "user_id": 13, "name": "Olive Ahearn", "longitude": "-7"},
{"latitude": "51.999447", "user_id": 14, "name": "Helen Cahill", "longitude": "-9.742744"},
{"latitude": "52.966", "user_id": 15, "name": "Michael Ahearn", "longitude": "-6.463"},
{"latitude": "52.366037", "user_id": 16, "name": "Ian Larkin", "longitude": "-8.179118"},
{"latitude": "54.180238", "user_id": 17, "name": "Patricia Cahill", "longitude": "-5.920898"},
{"latitude": "53.0033946", "user_id": 39, "name": "Lisa Ahearn", "longitude": "-6.3877505"},
{"latitude": "52.228056", "user_id": 18, "name": "Bob Larkin", "longitude": "-7.915833"},
{"latitude": "54.133333", "user_id": 24, "name": "Rose Enright", "longitude": "-6.433333"},
{"latitude": "55.033", "user_id": 19, "name": "Enid Cahill", "longitude": "-8.112"},
{"latitude": "53.521111", "user_id": 20, "name": "Enid Enright", "longitude": "-9.831111"},
{"latitude": "51.802", "user_id": 21, "name": "David Ahearn", "longitude": "-9.442"},
{"latitude": "54.374208", "user_id": 22, "name": "Charlie McArdle", "longitude": "-8.371639"},
{"latitude": "53.74452", "user_id": 29, "name": "Oliver Ahearn", "longitude": "-7.11167"},
{"latitude": "53.761389", "user_id": 30, "name": "Nick Enright", "longitude": "-7.2875"},
{"latitude": "54.080556", "user_id": 23, "name": "Eoin Gallagher", "longitude": "-6.361944"},
{"latitude": "52.833502", "user_id": 25, "name": "David Behan", "longitude": "-8.522366"}]

Main.java

package br.com.rmxs.intercom;

import br.com.rmxs.intercom.comparator.CustomerComparator;
import br.com.rmxs.intercom.entity.Customer;
import com.fasterxml.jackson.databind.ObjectMapper;

import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;


public class Main {
    private static String FILE_PATH = "resources/json/customers.json";
    private static final double OFFICE_LATITUDE = Math.toRadians(53.3381985);
    private static final double OFFICE_LONGITUDE = Math.toRadians(-6.2592576);
    private static final double R = 6371000; /** Meters **/
    private static final double PERIMETER = 100000.00; /** Meters **/

    public static void main(String[] args) {

        /** Read the file **/
        List<Customer> customers = readJsonFile();

        /** Process List **/
        customers = calculateNearCustomers(customers, R);

        /** Print Lines **/
        showLines(customers);

    }

    private static List<Customer> calculateNearCustomers(List<Customer> customers, double r) {
        List<Customer> filter = new ArrayList<Customer>();

        for(Customer customer : customers){
            double deltaLongitude = OFFICE_LONGITUDE - Math.toRadians(customer.getLongitude());
            double deltaSigma = Math.acos(
                    Math.sin(OFFICE_LATITUDE)*Math.sin(Math.toRadians(customer.getLatitude())) +
                    Math.cos(OFFICE_LATITUDE)*Math.cos(Math.toRadians(customer.getLatitude()))*Math.cos(deltaLongitude)
            );

            double distance = R * deltaSigma;

            if(distance <= PERIMETER){
                filter.add(customer);
            }
        }


        return filter;
    }

    public static List<Customer> readJsonFile(){
        try {
            FileReader reader = new FileReader(FILE_PATH);
            ObjectMapper mapper = new ObjectMapper();

            try {
                return mapper.readValue(reader, mapper.getTypeFactory().constructCollectionType(
                        List.class, Customer.class));
            } catch (IOException e) {
                e.printStackTrace();
            }
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }

        return new ArrayList<Customer>();
    }

    private static void showLines(List<Customer> customers){
        Collections.sort(customers, new CustomerComparator());

        System.out.println("==========================================================================");
        System.out.println("====================== Customers next to the office ======================");
        System.out.println("==========================================================================");
        for(Customer customer : customers){
            System.out.println(customer);
        }
    }

}